This invention relates generally to cylinder locks, and more particularly to a programable cylinder lock which allows for adapting the lock to operate upon insertion of a key having a different configuration than a key to which the lock was originally adapted.
In many organizations, such as businesses, apartment buildings, hotels, etc., it is generally desirable to customize the locks to the particular organization. There are two general methods by which keys and locks may be customized. A first method involves reconfiguring the drivers and tumblers in the lock so that a key with a particular top edge contour may operate the locks of the organization. The second method is by configuring the keyways in the locks to accept keys having a unique pattern of longitudinal contours formed in their sides. The purpose of the exclusivity generated by these methods is to prevent unauthorized entry into the organization. By this second method, it is not sufficient for opening the lock that one have a key having a top edge contour appropriate to the lock; the key must also include an appropriate longitudinal contour of grooves and/or ridges.
In general, standard locks include a housing which has a cylindrical bore therein. An elongated plug is rotatably mounted in the bore. A plurality of apertures extend through the housing and into the plug. A number of drivers and tumblers are positioned in these apertures and capable of being positioned in the plug and housing in such a manner as to allow for rotational movement of the plug in response to a main key inserted in the lock. The arrangement and construction of the lock provides for the drivers and/or tumblers to be positioned in the apertures between the plug and housing to prevent relative rotation between the plug and the housing when the wrong main key or no main key is inserted in the lock. However, the relative positioning of the drivers, tumblers, plug, and housing is such that, when the proper key is inserted, the drivers are positioned in the apertures substantially wholly within the housing and the tumblers are positioned in the apertures substantially wholly within the plug such that the plug can be rotated to an unlocking position. Many locks or sets of locks also include two types of keys: tenant keys and master keys. In general, each tenant key will only open one lock of a particular subset of locks, whereas a master key may open all the locks of the subset.
Over the course of time, the security of an organization may become compromised by the loss of control of one or more of the keys. For example, in apartment buildings, hotels, or motels, a guest or renter may leave and inadvertently or intentionally retain a key. When this occurs, subsequent occupants or tenants cannot be secure in their persons and property. Thus it would be desirable to easily and quickly reprogram the locks to accept a new key or set of keys. Locks that can be easily changed are also desired by businesses where several employees are in possession of keys to fit the locks. In such situations, an employee may be discharged or quit, but retain possession of a key. Further, an employee may lose a key, thus placing the security of the locked area in doubt.
When keys are lost or are possessed adversely, the general response is to change the locks fitting the lost key to require a key with a new top edge contour to correspond to different length tumblers. Generally, the shape of the longitudinal inner walls of the keyway which confronts the longitudinal contour on the side of the key is not changed due to the generally exorbitant cost of such a change.
The excessive expense of changing the pattern of the longitudinal walls of the keyway arises from the structure of the locks themselves. In general, as described above, locks designed for exclusive use by one organization include a plug rotatable within a lock housing for unlocking doors, etc. The key is inserted into a slot, or keyway, extending longitudinally into the plug and rotated to rotate the plug. Locks have generally been customized for a particular key blank by forming a set of ridges on the portions of the plug forming the walls of the keyway, the ridges extending parallel to the longitudinal axis of the keyway. The key blanks are provided with a corresponding set of grooves so that the ridges and grooves will mesh when the proper key is inserted into the keyway. If the key includes an improper pattern of longitudinal contours, the contour of the keyway will obstruct the key from being inserted.
Thus, in order to change the contour of the longitudinal inner walls of the keyway, it would be necessary to alter the plug in the lock. Since it is not economically feasible to add ridges within the narrow confines of a keyway, it is difficult to change the plug to prevent insertion of a key for which the plug and keyway were originally manufactured.
Previous attempts to correct the problems and drawbacks with replacing key blanks and redesigning the configuration of keyways in plugs have involved such methods as providing a set of bores which extend parallel to the longitudinal axis of the keyway and pins which slide in and out of the keyway with the end of the pins protruding into the pathway of the keyway. By removing and replacing and/or adding additional pins into the bores, the configuration of the wall of the keyway and thus the proper key to be inserted may be changed. However, this method requires removing and inserting the pins, which is a tedious and time consuming task.
Thus, it would be desirable to provide and construct a lock which permits rapid change the positioning of tumblers to accept a key of a different design. It would further be desirable to construct a lock to permit inexpensive change of keyway and key design. It would further be desirable to provide a lock which allows the operative key to be changed without removal of the plug from the lock, and/or other disassembly of the lock structure.
The present invention solves the problems and eliminates the drawbacks of locks as described in the background of the invention. The present invention does so by providing both an adaptable lock and a method of using the lock in order to reprogram the lock to accept a second key having a longitudinal contour different from a first key which originally operated the lock. This longitudinal contour may include ridges and/or grooves.
The lock includes a housing with a bore disposed through the housing and a plug rotatably mounted in the bore. This plug includes at least one first groove, referred to as a radial slot, disposed concentrically about and radially outwardly from the longitudinal axis of the plug. The plug further includes a first orifice, which may be a longitudinal slot used as a keyway, which is adapted to receive a key. The lock further includes first and second radial tumblers which are disposed in the radial slot. These first and second radial tumblers may be engaged with one another or disengaged from one another.
In one embodiment of the present invention, the engagement or disengagement of the first and second radial tumblers may be provided by the positioning of a retainer. When this retainer contacts the first radial tumbler, it moves the first radial tumbler into engagement with the second radial tumbler. When the retainer does not contact the first radial tumbler, the first and second radial tumblers disengage. When engaged, the first and second radial tumblers move cooperatively with one another. When disengaged, the second radial tumbler can move independently of the first radial tumbler. The distal ends of the first and second radial tumblers extend into the keyway and contact and engage the pattern created by the longitudinal contour of the key. An operator may move the retainer in and out of engagement with the first radial tumbler by inserting a reset tool into a second orifice, referred to as a reset slot, which intersects a cavity housing the retainer. This action lifts the retainer away from and out of engagement with the first radial tumbler, thus allowing the second radial tumbler to move independently of the first radial tumbler.
The method of using the lock of the present invention involves inserting a first key to which the lock is programmed to operate into the longitudinal keyway of the lock. The first and second radial tumblers are then disengaged one from another. The first key is then removed from the longitudinal slot and the second radial tumbler, now disengaged from the first radial tumbler, moves freely and independently of the first radial tumbler. The second key, having a different longitudinal contour than the first key, is then inserted into the reset slot. As this happens, the second radial tumbler moves to match the longitudinal contour of the second key. The first and second radial tumblers are then engaged with one another, thus placing them in a configuration adapted to the longitudinal contour of the second key.
Alternate embodiments of the invention may include multiple pairs of radial tumblers, each pair disposed in one of multiple radial slots disposed in the plug.
The method of reconfiguring the lock of the present invention as described above can be used to reconfigure the radial tumblers in order to change tenant keys which can properly operate the lock. Yet another embodiment of the present invention allows for changing the master keys which can properly operate the lock. In particular, this alternate embodiment allows for changing the configuration of the lock to accept a second master key having a different longitudinal contour than a first master key. In one such embodiment, a second set of radial tumblers, or a second set of multiple pairs of radial tumblers are disposed in a master radial slot or master radial slots located along the side of the plug opposite the radial tumblers used to program the lock for a tenant key.